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Guo DL, Zhang J, Yuen ST, Tsui WY, Chan ASY, Ho C, Ji J, Leung SY, Chen X. Reduced expression of EphB2 that parallels invasion and metastasis in colorectal tumours. Carcinogenesis 2005; 27:454-64. [PMID: 16272170 DOI: 10.1093/carcin/bgi259] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
EphB2, a receptor tyrosine kinase regulated by the beta-catenin/Tcf4 complex, is expressed in the proliferative compartment of mouse intestine and regulates bidirectional migration of intestinal precursor cells in the crypt-villus axis through repulsive interaction with Ephrin-B ligands. Recently, it has been shown that reduction of EphB activity accelerates colon tumour progression in the Apc(Min/+) mice. In this study, we examined the expression of EphB2 in normal colon, adenomas, primary colorectal cancers (CRCs), lymph node metastases and liver metastases using immunohistochemistry on tissue microarrays. In addition, EphB2 was overexpressed in SW480 colon cancer cells to study its effect in vitro. We found that EphB2 was expressed in 100% of normal colon crypt base cells, 78% of adenomas, 55.4% of primary CRCs, 37.8% of lymph node metastases and 32.9% of liver metastases (all differences were statistically significant at P < 0.001 compared with primary CRCs). Patients with CRCs that lose EphB2 expression had more advanced tumour stage (P = 0.005), poor differentiation (P < 0.001), poor overall survival (P = 0.005) and disease-free survival (P = 0.001), with the latter being independent of tumour stage. In vitro studies showed that overexpression of EphB2 inhibited colon cancer cell growth in colony formation assay and activation of EphB2 receptor inhibited colon cancer cell adhesion and migration. Our data demonstrated a progressive loss of EphB2 expression in each critical step of colon carcinogenesis, including the onset of invasion, dedifferentiation and metastasis which are paralleled by adverse patient outcome. EphB2 may achieve its tumour suppressor function through regulation of cell survival, adhesion and migration.
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Wong CW, Fan YS, Chan TL, Chan ASW, Ho LC, Ma TKF, Yuen ST, Leung SY. BRAF and NRAS mutations are uncommon in melanomas arising in diverse internal organs. J Clin Pathol 2005; 58:640-4. [PMID: 15917418 PMCID: PMC1770697 DOI: 10.1136/jcp.2004.022509] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2004] [Indexed: 01/22/2023]
Abstract
BACKGROUND Malignant melanoma arising from different body compartments may be associated with differing aetiological factors and clinical behaviour, and may manifest diverse molecular genetic profiles. Although many studies have focused on cutaneous melanoma, little is known of mucosal and other types of melanoma. In particular, malignant melanoma of soft parts is different from other melanomas in many respects, yet manifests a common melanocytic differentiation. Mutation of BRAF is now known to be common in cutaneous melanomas, and raises possible new therapeutic options of anti-RAF treatment for these patients. Few data are available for non-cutaneous melanomas. AIMS To study the incidence of BRAF and NRAS mutations in melanomas arising in diverse internal organs. METHODS Fifty one melanomas from various internal organs were investigated for BRAF and NRAS mutation by direct DNA sequencing. RESULTS BRAF and NRAS mutations were found in two and five mucosal melanomas arising from the aerodigestive and female genital tracts (n = 36). Their occurrence is mutually exclusive, giving a combined mutation incidence rate of 19.4% in mucosal melanomas. Both BRAF and NRAS mutations were absent in malignant melanoma of soft parts (n = 7). BRAF mutation was also absent in uveal melanoma (n = 6), but was seen in two of five cutaneous melanomas. The incidence of BRAF or combined BRAF/NRAS mutations in all non-cutaneous groups was significantly lower than published rates for cutaneous melanomas. CONCLUSION Each melanoma subtype may have a unique oncogenetic pathway of tumour development, and only a small fraction of non-cutaneous melanomas may benefit from anti-RAF treatment.
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Li VSW, Wong CW, Chan TL, Chan ASW, Zhao W, Chu KM, So S, Chen X, Yuen ST, Leung SY. Mutations of PIK3CA in gastric adenocarcinoma. BMC Cancer 2005; 5:29. [PMID: 15784156 PMCID: PMC1079799 DOI: 10.1186/1471-2407-5-29] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2004] [Accepted: 03/23/2005] [Indexed: 12/12/2022] Open
Abstract
Background Activation of the phosphatidylinositol 3-kinase (PI3K) through mutational inactivation of PTEN tumour suppressor gene is common in diverse cancer types, but rarely reported in gastric cancer. Recently, mutations in PIK3CA, which encodes the p110α catalytic subunit of PI3K, have been identified in various human cancers, including 3 of 12 gastric cancers. Eighty percent of these reported mutations clustered within 2 regions involving the helical and kinase domains. In vitro study on one of the "hot-spot" mutants has demonstrated it as an activating mutation. Methods Based on these data, we initiated PIK3CA mutation screening in 94 human gastric cancers by direct sequencing of the gene regions in which 80% of all the known PIK3CA mutations were found. We also examined PIK3CA expression level by extracting data from the previous large-scale gene expression profiling study. Using Significance Analysis of Microarrays (SAM), we further searched for genes that show correlating expression with PIK3CA. Results We have identified PIK3CA mutations in 4 cases (4.3%), all involving the previously reported hotspots. Among these 4 cases, 3 tumours demonstrated microsatellite instability and 2 tumours harboured concurrent KRAS mutation. Data extracted from microarray studies showed an increased expression of PIK3CA in gastric cancers when compared with the non-neoplastic gastric mucosae (p < 0.001). SAM further identified 2910 genes whose expression levels were positively associated with that of PIK3CA. Conclusion Our data suggested that activation of the PI3K signalling pathway in gastric cancer may be achieved through up-regulation or mutation of PIK3CA, in which the latter may be a consequence of mismatch repair deficiency.
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Leung PWL, Lee CC, Hung SF, Ho TP, Tang CP, Kwong SL, Leung SY, Yuen ST, Lieh-Mak F, Oosterlaan J, Grady D, Harxhi A, Ding YC, Chi HC, Flodman P, Schuck S, Spence MA, Moyzis R, Swanson J. Dopamine receptor D4 (DRD4) gene in Han Chinese children with attention-deficit/hyperactivity disorder (ADHD): increased prevalence of the 2-repeat allele. Am J Med Genet B Neuropsychiatr Genet 2005; 133B:54-6. [PMID: 15578612 DOI: 10.1002/ajmg.b.30129] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
There is an increased prevalence of the 7-repeat (7R) allele of the dopamine receptor D4 (DRD4) gene in attention-deficit/hyperactivity disorder (ADHD). However, the population prevalence of the 7R allele varies considerably across ethnicity and is very low in Asians. To test whether this 7R allele/ADHD association still held in a Chinese clinical sample, 32 Han Chinese children with a confirmed ADHD diagnosis and normal IQ who were methylphenidate-responders were genotyped. None of them had a DRD4 7R allele. Instead, we observed a significantly increased prevalence of the 2-repeat (2R) allele in this clinical sample (33%) compared to ethnically-matched controls (20%) (chi(2)(1d.f.) = 5.90, P = 0.015). This approximately 1.65-fold increase of the 2R allele in our probands is close to the observed increase of the 7R allele in European-ancestry ADHD children. Recent genetic studies have indicated that the 2R allele in Asians is likely derived from the 7R allele. Further, available biochemical data indicate that both the 2R and 7R protein have blunted responses to dopamine compared to the 4R protein. Based on these results, we propose that the observed increased prevalence of the 2R allele in our Han Chinese ADHD probands is still consistent with the 7R allele hypothesis of ADHD in European-ancestry children. Recent studies have suggested that any variant from the conserved ancestral 4R allele might potentially alter biochemistry/phenotype. We hypothesize that an increased frequency of any non-4R allele may define the association of the DRD4 gene with ADHD that holds across ethnicity. The present findings, however, obtained with a small ADHD sample size, should be replicated.
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He QY, Cheung YH, Leung SY, Yuen ST, Chu KM, Chiu JF. Diverse proteomic alterations in gastric adenocarcinoma. Proteomics 2004; 4:3276-87. [PMID: 15378696 DOI: 10.1002/pmic.200300916] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Gastric adenocarcinoma is one of the most common cancers in Asian countries including China. Although its incidence rates in the West are lower than that in Asia, gastric cancer is still a major health problem worldwide, being second only to lung cancers in the number of deaths it causes. Helicobacter pylori infection has been identified as the major pathogen, but the detailed pathogenesis of gastric carcinoma remains elusive. Due to the lack of suitable and specific biomarkers for early detection, most cases of the disease are diagnosed at late stages and the survival rate is low. In this study, we used a proteomic approach to globally analyze the protein profiles of paired surgical specimens of primary gastric adenocarcinoma and nontumor mucosa aiming at identifying specific disease-associated proteins as potential clinical biomarkers and for carcinogenetic study. Compared to nontumor tissues, multiple protein alterations were found in tumor tissues. Some of these alterations involve variations in the expression of cytoskeleton proteins, including an increase in cytokeratin 8 and tropomyosin isoform and a decrease in cytokeratin 20. Co-up-regulations of heat-shock proteins and glycolytic enzymes were observed in tumor tissues, indicating self-protective efforts of cells and the growing energy requirement during malignant transformation. Diverse regulations also occurred with proteins involved in cell proliferation and differentiation, such as GMP reductase 2 and creatine kinase B, and proteins bearing potential tumor suppressor activities, including prohibitin and selenium binding protein 1. More interestingly, a human stomach-specific protein, 18 kDa antrum mucosa protein, was found to be dramatically under-expressed in cancer tissues, implicating a possible special pathological role for this protein in gastric carcinogenesis. Further comprehensive evaluation by globally considering the altered factors may result in the discovery of a biomarker index for effective assessment of the disease and may provide in-depth information for better understanding the pathogenesis of gastric cancer.
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Subramanian S, West RB, Corless CL, Ou W, Rubin BP, Chu KM, Leung SY, Yuen ST, Zhu S, Hernandez-Boussard T, Montgomery K, Nielsen TO, Patel RM, Goldblum JR, Heinrich MC, Fletcher JA, van de Rijn M. Gastrointestinal stromal tumors (GISTs) with KIT and PDGFRA mutations have distinct gene expression profiles. Oncogene 2004; 23:7780-90. [PMID: 15326474 DOI: 10.1038/sj.onc.1208056] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Most GISTs require oncogenic activation of the KIT or PDGFRA receptor tyrosine kinase proteins, and the genomic mechanisms of oncogene activation are heterogeneous. Notably, the kinase mutation type correlates with both tumor biology and imatinib response. For example, GISTs with KIT exon 11 mutations are typically gastric and have excellent imatinib response, whereas those with KIT exon 9 mutations generally arise in the small bowel and are less responsive to imatinib. To identify genes that might contribute to these biological differences, we carried out gene expression profiling of 26 GISTs with known KIT and PDGFRA mutational status. Expression differences were then evaluated further by RNA in situ hybridization, immunohistochemistry, and immunoblotting. Unsupervised hierarchical clustering grouped tumors with similar mutations together, but the distinction between the different groups was not absolute. Differentially expressed genes included ezrin, p70S6K, and PKCs, which are known to have key roles in KIT or PDGFRA signaling, and which might therefore contribute to the distinctive clinicopathological features in GISTs with different mutation types. These gene products could serve as highly selective therapeutic targets in GISTs containing the KIT or PDGFRA mutational types with which they are associated.
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Leung SY, Yuen ST, Chu KM, Mathy JA, Li R, Chan ASY, Law S, Wong J, Chen X, So S. Expression profiling identifies chemokine (C-C motif) ligand 18 as an independent prognostic indicator in gastric cancer. Gastroenterology 2004; 127:457-69. [PMID: 15300578 DOI: 10.1053/j.gastro.2004.05.031] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Gastric cancer is one of the major cancers worldwide. Expression profiling has proven useful in delineating novel prognostic markers in various cancer types. We previously analyzed gene-expression patterns in 90 gastric adenocarcinomas by using complementary DNA microarrays and prioritized a list of genes whose expression levels predict patient outcome. METHODS We identified a specific gene of interest, chemokine (C-C motif) ligand 18 (CCL18), on the basis of a high absolute standardized log Cox hazard ratio, a high variance in expression among all tumor samples, and putative biologic function. Detailed analysis of CCL18 expression with clinicopathologic and survival data was performed (n = 89). Quantitative reverse-transcription polymerase chain reaction was used to verify the microarray expression data and was further applied to analyze an independent cohort of tumor samples (n = 59). The cellular source of CCL18 was determined with immunohistochemistry and in situ hybridization. RESULTS High CCL18 expression levels were associated with prolonged overall (P = 0.001; hazard ratio, 0.586) and disease-free (P = 0.002; hazard ratio, 0.416) patient survival in the array-based data set by univariate analysis. The observations were confirmed in an independent set of 59 patients by using quantitative reverse-transcription polymerase chain reaction. In multivariate analysis, tumor stage and CCL18 levels were independent prognostic factors for predicting both overall and disease-free survival. We found that CCL18 was expressed by a subpopulation of tumor-associated macrophages that were preferentially located at the tumor invasion front. CONCLUSIONS Macrophage-derived CCL18 may function as a local antitumor immunomodulator that affects patient outcome. Our study suggests CCL18 as a novel candidate for antitumor therapeutics and risk stratification in gastric cancer patients.
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Xia HHX, Yang Y, Lam SK, Wong WM, Leung SY, Yuen ST, Elia G, Wright NA, Wong BCY. Aberrant epithelial expression of trefoil family factor 2 and mucin 6 in Helicobacter pylori infected gastric antrum, incisura, and body and its association with antralisation. J Clin Pathol 2004; 57:861-6. [PMID: 15280409 PMCID: PMC1770377 DOI: 10.1136/jcp.2003.015487] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 02/07/2023]
Abstract
AIMS To determine gastric expression of trefoil family factor 2 (TFF2) and MUC6 in Helicobacter pylori positive and negative subjects, and its association with antralisation at the gastric incisura. METHODS Gastric biopsies from the antrum, incisura, and body of 76 dyspeptic patients without ulcers were used for the determination of H. pylori infection, histological changes, and epithelial TFF2 and MUC6 expression. RESULTS In the foveola, the rates of TFF2 and MUC6 immunostaining were greater in H. pylori infected (n = 27) than in uninfected patients (n = 49) at the antrum (59.3% v 4.1% for TFF2 and 63.0% v 4.1% for MUC6; both p < 0.001) and incisura (44.4% v 2.0% for TFF2 and 48.1% v 0% for MUC6; both p < 0.001). In the deeper glands, the rates were also greater in H. pylori infected than in uninfected patients at the incisura (85.2% v 22.4% for both TFF2 and MUC6; p < 0.001). Antral-type mucosa was present at the incisura in 28 of the 76 patients. TFF2 and MUC6 expression in the foveola and deeper glands was significantly associated with antral-type mucosa, independent of H. pylori status. CONCLUSIONS Helicobacter pylori infection increases the expression of TFF2 and MUC6 in the gastric epithelium. Aberrant TFF2 and MUC6 expression is associated with antralisation of gastric incisura.
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Chan TL, Chan YW, Ho JWC, Chan C, Chan ASY, Chan E, Lam PWY, Tse CW, Lee KC, Lau CW, Gwi E, Leung SY, Yuen ST. MSH2 c.1452-1455delAATG is a founder mutation and an important cause of hereditary nonpolyposis colorectal cancer in the southern Chinese population. Am J Hum Genet 2004; 74:1035-42. [PMID: 15042510 PMCID: PMC1181966 DOI: 10.1086/383591] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Accepted: 02/09/2004] [Indexed: 01/20/2023] Open
Abstract
Hereditary nonpolyposis colorectal cancer (HNPCC) accounts for approximately 2% of all colorectal cancer (CRC) cases and is the most common hereditary CRC syndrome. We have previously reported a high incidence of microsatellite instability (MSI) and germline mismatch repair (MMR) gene mutations in young Hong Kong Chinese with CRC. Ongoing studies at the Hereditary Gastrointestinal Cancer Registry in Hong Kong have revealed a unique germline MSH2 c.1452-1455delAATG mutation that has not been reported in other ethnic groups. Detailed analysis showed that this specific MSH2 mutation constituted 21% of all germline MMR gene mutations and 36% of all MSH2 germline mutations identified. We designed a specific PCR-based diagnostic test on paraffin-embedded tissues and identified this germline mutation in 2 (1.5%) of 138 consecutive patients with early-onset CRC (<46 years of age at diagnosis). Haplotype analysis was performed using 11 microsatellite markers located between D2S391 and D2S123. All 10 families had the same disease haplotype, suggesting a founder effect. These 10 families all originated from the Chinese province of Guangdong, which historically included Hong Kong. It is the most populous of the Chinese provinces, with a population of >93 million. Further analysis suggested that this founder mutation may date back to between 22 and 103 generations ago. The identification of this MSH2 founder mutation has important implications for the design of mutation-detection strategies for the southern Chinese population. Since there were major emigrations from Hong Kong and Guangdong province during the 19th and 20th centuries, this finding is also significant for Chinese communities worldwide.
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85
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Chan SC, Cheung ST, Leung SY, Liu CL, Fan ST, Lo CM. De novo sarcoma of donor origin in a liver allograft determined by microsatellite analysis: a short report. Liver Transpl 2004; 10:320-3. [PMID: 14762874 DOI: 10.1002/lt.20063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This case report describes a patient who underwent liver transplantation for HBV cirrhosis for hepatocellular carcinoma [corrected]. At 3.5 years post transplant, 6 cm tumor was found with CT scanning. With microsatellite analysis it was determined that the tumor was of donor origin. The patient underwent successful right hepatectomy of the tumor that proved to be sarcoma. The patient is doing well without recurrence 1.5 years after resection and 5 years post transplant.
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Wong BCY, Lam SK, Wong WM, Chen JS, Zheng TT, Feng RE, Lai KC, Hu WHC, Yuen ST, Leung SY, Fong DYT, Ho J, Ching CK, Chen JS. Helicobacter pylori eradication to prevent gastric cancer in a high-risk region of China: a randomized controlled trial. JAMA 2004; 291:187-94. [PMID: 14722144 DOI: 10.1001/jama.291.2.187] [Citation(s) in RCA: 982] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
CONTEXT Although chronic Helicobacter pylori infection is associated with gastric cancer, the effect of H pylori treatment on prevention of gastric cancer development in chronic carriers is unknown. OBJECTIVE To determine whether treatment of H pylori infection reduces the incidence of gastric cancer. DESIGN, SETTING, AND PARTICIPANTS Prospective, randomized, placebo-controlled, population-based primary prevention study of 1630 healthy carriers of H pylori infection from Fujian Province, China, recruited in July 1994 and followed up until January 2002. A total of 988 participants did not have precancerous lesions (gastric atrophy, intestinal metaplasia, or gastric dysplasia) on study entry. INTERVENTION Patients were randomly assigned to receive H pylori eradication treatment: a 2-week course of omeprazole, 20 mg, a combination product of amoxicillin and clavulanate potassium, 750 mg, and metronidazole, 400 mg, all twice daily (n = 817); or placebo (n = 813). MAIN OUTCOME MEASURES The primary outcome measure was incidence of gastric cancer during follow-up, compared between H pylori eradication and placebo groups. The secondary outcome measure was incidence of gastric cancer in patients with or without precancerous lesions, compared between the 2 groups. RESULTS Among the 18 new cases of gastric cancers that developed, no overall reduction was observed in participants who received H pylori eradication treatment (n = 7) compared with those who did not (n = 11) (P =.33). In a subgroup of patients with no precancerous lesions on presentation, no patient developed gastric cancer during a follow-up of 7.5 years after H pylori eradication treatment compared with those who received placebo (0 vs 6; P =.02). Smoking (hazard ratio [HR], 6.2; 95% confidence interval [CI], 2.3-16.5; P<.001) and older age (HR, 1.10; 95% CI, 1.05-1.15; P<.001) were independent risk factors for the development of gastric cancer in this cohort. CONCLUSIONS We found that the incidence of gastric cancer development at the population level was similar between participants receiving H pylori eradication treatment and those receiving placebo during a period of 7.5 years in a high-risk region of China. In the subgroup of H pylori carriers without precancerous lesions, eradication of H pylori significantly decreased the development of gastric cancer. Further studies to investigate the role of H pylori eradication in participants with precancerous lesions are warranted.
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Zhao W, Chan TL, Chu KM, Chan AS, Stratton MR, Yuen ST, Leung SY. Mutations of BRAF and KRAS in gastric cancer and their association with microsatellite instability. Int J Cancer 2003; 108:167-9. [PMID: 14618633 DOI: 10.1002/ijc.11553] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Chan ASW, Tsui WY, Chen X, Chu KM, Chan TL, Chan ASY, Li R, So S, Yuen ST, Leung SY. Downregulation of ID4 by promoter hypermethylation in gastric adenocarcinoma. Oncogene 2003; 22:6946-53. [PMID: 14534543 DOI: 10.1038/sj.onc.1206799] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Promoter hypermethylation has become apparent as a common mechanism of gene silencing in cancer. Based on our published microarray expression data, we noticed a prominent downregulation of ID4 in gastric adenocarcinoma. The dense 5' CpG island covering the previously mapped upstream promoter of ID4 has prompted us to relate its downregulation to promoter hypermethylation. ID proteins are distinct members in the helix-loop-helix family of transcriptional regulators, which modulate various key developmental processes. Emerging data have suggested the involvement of ID genes in tumorigenesis. In this study using bisulfite genomic sequencing, we have found hypermethylation of ID4 promoter in most gastric cancer cell lines and 30% of primary tumors. This correlated with decreased level of ID4 expression. Restoration of ID4 expression in various gastric cancer cell lines was achieved by treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine, which at times required the synergistic action of the histone deacetylase inhibitor trichostatin A, but not with trichostatin A alone. Re-expression was accompanied by the corresponding ID4 promoter demethylation. Furthermore, we have found significant association of ID4 promoter methylation with hMLH1 promoter methylation (P=0.008) and microsatellite instability (P=0.006). Overall, our results have shown that transcriptional silencing of ID4 is related to the aberrant methylation of its promoter in gastric cancer. The significant association of ID4 and hMLH1 promoter hypermethylation suggested that ID4 may also be among the genes being targeted in the CpG island methylator phenotype tumorigenic pathway.
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Xia HHX, Lam SK, Wong WM, Hu WHC, Lai KC, Wong SH, Leung SY, Yuen ST, Wright NA, Wong BCY. Antralization at the edge of proximal gastric ulcers: does Helicobacter pylori infection play a role? World J Gastroenterol 2003; 9:1265-9. [PMID: 12800237 PMCID: PMC4611797 DOI: 10.3748/wjg.v9.i6.1265] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM To determine the prevalence of antralization at the edge of proximal gastric ulcers, and the effect of H. pylori eradication on the mucosal appearances. METHODS Biopsies were taken from the antrum, body and the ulcer edge of patients with benign proximal gastric ulcers before and one year after treatment. Gastric mucosa was classified as antral, transitional or body type. H. pylori positive patients received either triple therapy, or omeprazole. RESULTS Patients with index ulcers in the incisura, body or fundus (n=116) were analyzed. Antral-type mucosa was more prevalent at the ulcer edge in H. pylori-positive patients than H. pylori-negative patients (93 % vs 60 %, OR=8.95, 95 %CI: 2.47-32.4, P=0.001). At one year, there was a significant reduction in the prevalence of antralization (from 93 % to 61 %, P=0.004) at the ulcer edge in patients with H. pylori being eradicated. However, there was no difference in the prevalence of antralization at the ulcer edge in those with persistent infection. CONCLUSION H. pylori infection is associated with antralization at the edge of proximal gastric ulcers, which may be reversible in some patients after eradication of the infection.
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Chu KM, Yuen ST, Wong WM, Wong KW, Lai KC, Hu WHC, Leung SY, Yuen MF, Lam SK, Wong BCY. A prospective comparison of performance of biopsy forceps used in single passage with multiple bites during upper endoscopy. Endoscopy 2003; 35:338-42. [PMID: 12664392 DOI: 10.1055/s-2003-38147] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
BACKGROUND AND STUDY AIMS A single biopsy is usually obtained for each passage of a biopsy forceps. It was hypothesized that multiple bites per passage might improve the quantity and quality of tissue obtained, without significant artifacts. This hypothesis was tested in a prospective, pathologist-blinded study using different forceps. PATIENTS AND METHODS Forty consecutive patients who underwent elective upper endoscopy were included. Five different forceps were used in six different ways, varying in the number of bites taken per passage. Two pathologists, who were blinded to the type of biopsy forceps used, evaluated the specimens according to the parameters of maximum weight (mg), size of largest fragment (mm), depth, squash artifact, adequacy, and overall rating. RESULTS A total of 240 biopsy specimens were obtained. The Microvasive Multibite and Megabite forceps obtained specimens with the maximum weight (P<0.05) and the largest size (P<0.05), respectively. Alligator forceps were able to obtain specimens significantly larger in size than the oval-shaped forceps (P<0.05). The Olympus FB-24K forceps performed best in both the adequacy score and the overall rating score (P<0.05). CONCLUSIONS Forceps with a needle, or the Multibite forceps, allow more biopsies to be taken per passage and improve the quality of tissues obtained. "Needleless" forceps can be used to obtain two samples per passage through the endoscope that are as good as when only one sample is collected. This approach can save time, and causes no significant damage to the biopsy specimens.
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Tsao SW, Liu Y, Wang X, Yuen PW, Leung SY, Yuen ST, Pan J, Nicholls JM, Cheung ALM, Wong YC. The association of E-cadherin expression and the methylation status of the E-cadherin gene in nasopharyngeal carcinoma cells. Eur J Cancer 2003; 39:524-31. [PMID: 12751385 DOI: 10.1016/s0959-8049(02)00494-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Loss of E-cadherin (E-cad) has been associated with progression and poor survival in nasopharyngeal carcinoma (NPC). In this study, we investigated the role of methylation on E-cad inactivation in NPC cell lines, as well as in NPC tissue samples. Using 6 NPC cell lines, we found that methylation of the E-cad 5' CpG island promoter region was correlated with the loss of both mRNA and E-cad protein expression in these cell lines. In addition, using 29 NPC and 10 non-malignant nasopharyngeal samples, we also observed 5' CpG methylation of the E-cad gene in 52% (15 out of 29) NPC samples, but in only 10% (1 out of 10) of the non-malignant nasopharyngeal tissues. Our findings indicate that 5' CpG island methylation of the E-cad gene may play an important part in the inactivation of E-cad in NPC. Our results also suggest that reducing the methylation of the E-cad gene may be a potential therapeutic strategy for NPC.
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Yuen ST, Chan TL, Ho JWC, Chan ASY, Chung LP, Lam PWY, Tse CW, Wyllie AH, Leung SY. Germline, somatic and epigenetic events underlying mismatch repair deficiency in colorectal and HNPCC-related cancers. Oncogene 2002; 21:7585-92. [PMID: 12386821 DOI: 10.1038/sj.onc.1205968] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2002] [Revised: 08/08/2002] [Accepted: 08/08/2002] [Indexed: 11/08/2022]
Abstract
High-frequency microsatellite instability (MSI-H) results from deficiency in nucleotide mismatch repair. It contributes significantly to carcinogenesis in the human colorectal mucosa. Here we study 41 colorectal and three other HNPCC-related cancers with MSI-H to provide comprehensive information on the mechanisms of inactivation of the two major proteins involved, hMLH1 and hMSH2. Seventeen of the patients had family histories meeting the criteria for Bethesda grades 1, 2 or 3. Of these familial cases, 14 (83%) had early-onset disease, defined on the basis of diagnosis prior to the age of 50, but in three the disease was of late onset (>50 years). A second subset of 20 patients had early onset disease without family history. The remaining seven patients were selected to allow comparisons with sporadic, late-onset disease, the molecular basis of which has been extensively reported elsewhere. We stratified the tumours initially on the basis of hMLH1 or hMSH2 protein deficiency, detected by immunohistochemistry, and then by analysis of germline and somatic mutation, mRNA transcription, loss of heterozygosity (LOH) at the hMLH1 and hMSH2 loci, and methylation status in two regions of the hMLH1 promoter. The functional significance of several of these changes in the MSI-H tumours was confirmed by comparisons with 16 tumours with low-frequency microsatellite instability and 56 tumours with stable microsatellites. As anticipated, patients with family histories usually showed germline mutation of hMSH2 or hMLH1. In many cases the residual normal allele was silenced in their tumours by loss of heterozygosity (LOH). The small subset of late-onset, sporadic cases confirmed the preponderance in this group of biallelic hMLH1 promoter methylation. In the early-onset, apparently sporadic subset there were 11 tumours with hMLH1 deficiency, five with hMSH2 deficiency and four with no detectable abnormality in expression of either protein. These showed a complex mixture of lesions, including germline and somatic mutations, promoter methylation, LOH, suppression of wild-type RNA by as yet undiscovered mechanisms, or no detectable abnormality in any of these parameters. Evidence is presented to indicate that methylation in proximal region of the hMLH1 promoter is a more reliable correlate of transcriptional silencing in colorectal cancers than methylation in upstream region. These observations have significant implications for management of patients with MSI-H tumours.
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Ji J, Chen X, Leung SY, Chi JTA, Chu KM, Yuen ST, Li R, Chan ASY, Li J, Dunphy N, So S. Comprehensive analysis of the gene expression profiles in human gastric cancer cell lines. Oncogene 2002; 21:6549-56. [PMID: 12226758 DOI: 10.1038/sj.onc.1205829] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2002] [Revised: 06/13/2002] [Accepted: 06/28/2002] [Indexed: 01/14/2023]
Abstract
Gastric adenocarcinoma is one of the major malignancies worldwide. Gastric cell lines have been widely used as the model to study the genetics, pharmacology and biochemistry of gastric cancers. Here we describe a comprehensive survey of the gene expression profiles of 12 gastric carcinoma cell lines, using cDNA microarray with 43 000 clones. For comparison, we also explored the gene expression patterns of 15 cell lines derived from lymphoid, endothelial, stromal and other epithelial cancers. Expression levels of specific genes were validated through comparison to protein expression by immunohistochemistry using cell block arrays. We found sets of genes whose expression corresponds to the molecular signature of each cell type. In the gastric cancer cell lines, apart from genes that are highly expressed corresponding to their common epithelial origin from the gastrointestinal tract, we found marked heterogeneity among the gene expression patterns of these cell lines. Some of the heterogeneity may reflect their underlying molecular characteristics or specific differentiation program. Two putative gastric carcinoma cell lines were found to be B-cell lymphoma, and another one had no epithelial specific gene expression and hence was of doubtful epithelial origin. These cell lines should no longer be used in gastric carcinoma research. In conclusion, our gene expression database can serve as a powerful resource for the study of gastric cancer using these cell lines.
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Ng FH, Lai KC, Wong BCY, Wong WM, Wong SY, Chow KC, Yuen ST, Leung SY, Lam SK. [13C]-urea breath test without prior fasting and without test meal is accurate for the detection of Helicobacter pylori infection in Chinese. J Gastroenterol Hepatol 2002; 17:834-8. [PMID: 12164957 DOI: 10.1046/j.1440-1746.2002.02833.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Conventional [13C]-urea breath test ([13C]-UBT) requires prior fasting and a test meal, which theoretically improves the accuracy of the test. However, recent studies have suggested that prior fasting and test meal may not be essential. We aimed to determine the accuracy of a new [13C]-UBT protocol without fasting in Chinese. METHODS Dyspeptic patients referred for upper endoscopy were recruited. The gold standard for Helicobacter pylori infection was the combination of Campylobacter-like organism (CLO) test and histology. Group I (n = 213) patients underwent [13C]-UBT with prior fasting and with citrate acid test meal. Group II (n = 123) patients underwent [13C]-UBT without prior fasting but with test meal. Group III (n = 90) patients underwent [13C]-UBT without prior fasting and without test meal. RESULTS The highest accuracy for groups I, II and III was 96.7, 95.1 and 95.5% using a cut-off value of 5.0, 5.5 and 3.5, respectively. The sensitivities and specificities were 97.4 and 95.8% in group I, 93.3 and 96.8% in group II, and 96.5 and 93.9% in group III, respectively. CONCLUSION The [13C]-UBT protocols without prior fasting and either with or without test meal produce highly accurate and reliable results in the Chinese population.
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95
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Wong WM, Wong BC, Tang VS, Lai KC, Yuen ST, Leung SY, Hu WH, Lam SK. An evaluation of the PyloriTek test for the diagnosis of Helicobacter pylori infection in Chinese patients before and after eradication therapy. J Gastroenterol Hepatol 2001; 16:976-80. [PMID: 11595060 DOI: 10.1046/j.1440-1746.2001.02565.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND AIM The PyloriTek Test Kit (a 1-h rapid urease test) was developed for the rapid diagnosis of Helicobacter pylori (H. pylori) during endoscopy. Most studies were performed in Western populations. The aim of this study was to evaluate the PyloriTek test for the diagnosis of H. pylori infection in Chinese population. METHODS Eligible patients without prior treatment or who had had recent eradication of H. pylori were recruited. During endoscopy, biopsies were taken from the antrum and corpus for an in-house rapid urease test (RUT), histology and for the PyloriTek test (one antral and one corpus biopsy). Results of the PyloriTek test were compared with the gold standard (RUT and histology). RESULTS Analysis of PyloriTek test results from the antrum alone (101 patients before eradication and 52 patients after eradication) showed a sensitivity, specificity, and accuracy of 96.3, 97.9, and 97.0%, respectively, for cases before eradication, and an accuracy of 100% for cases after eradication. The benefit of an additional body biopsy was marginal and only occurred in the pre-eradication group. CONCLUSION The PyloriTek test was highly accurate for the diagnosis of H. pylori infection before and after eradication therapy, with a final result available at 1 h, which is unmatched by any invasive test so far. It enhances clinical decision-making by allowing the clinicians or endoscopists to start therapy on the same day of an endoscopy visit. One biopsy from the antrum is highly reliable for this purpose.
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96
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Fan XM, Wong BC, Wang WP, Zhou XM, Cho CH, Yuen ST, Leung SY, Lin MC, Kung HF, Lam SK. Inhibition of proteasome function induced apoptosis in gastric cancer. Int J Cancer 2001; 93:481-8. [PMID: 11477551 DOI: 10.1002/ijc.1373] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The ubiquitin-proteasome pathway plays a critical role in the degradation of cellular proteins and cell cycle control. Dysregulating the degradation of such proteins should have profound effects on tumor growth and causes cells to undergo apoptosis. The aims of this study are to evaluate the ubiquitin-proteasome pathway in gastric cancer and the potential role of pharmacological inhibition of proteasome on induction of apoptosis in gastric cancer cells. Gastric cancer cell lines AGS (p53 wild-type) and MKN-28 (p53 mutant) were treated with proteasome inhibitor MG132. The results showed that MG132 inhibited cell proliferation in AGS and MKN-28 cells in a time- and dose-dependent manner. The inhibition of cell proliferation was caused by apoptosis which was also time- and dose-dependent. AGS cells were more responsive to MG132 than MKN-28 cells. Induction of apoptosis was preceded by the activation of caspase-3, as measured by a colorimetric caspase-3 cellular activity and Western blotting of the cleavage of caspase-3 and its substrate PARP. Activation of caspase-7 was also exhibited. In addition, z-VAD-fmk, a broad spectrum caspase inhibitor, reversed apoptosis induced by MG132 in AGS and MKN28 cells. Although z-DEVD-fmk, a specific caspase-3 inhibitor, suppressed MG132-induced apoptosis in MKN28 cells, it only partially rescued the apoptotic effect in AGS cells. Caspase-3 activation was the result of release of cytochrome c from mitochondria into the cytosol, as a consequence of upregulation of bax. There were overexpressions of all the proteasome-related proteins p53, p21(waf1) and p27(kip1) at 4 hr after proteasome inhibition which was identified by the accumulation of ubiquitin-tagged proteins. This was accompanied by accumulation of cells at G(1) phase. Our present study suggests that inhibition of proteasome function in gastric cancer cells induces apoptosis and proteasomal inhibitors have potential use as novel anticancer drugs in gastric cancer.
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Chan TL, Curtis LC, Leung SY, Farrington SM, Ho JW, Chan AS, Lam PW, Tse CW, Dunlop MG, Wyllie AH, Yuen ST. Early-onset colorectal cancer with stable microsatellite DNA and near-diploid chromosomes. Oncogene 2001; 20:4871-6. [PMID: 11521198 DOI: 10.1038/sj.onc.1204653] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2001] [Revised: 02/27/2001] [Accepted: 05/23/2001] [Indexed: 12/25/2022]
Abstract
Colorectal cancer has been described in terms of genetic instability selectively affecting either microsatellite sequences (MIN) or chromosome number and structure (CIN). A subgroup with apparently stable, near-diploid chromosomes and stable microsatellites (MACS) also exists. These distinctions are important, partly because of their value in highlighting different pathways of carcinogenesis, and partly because of their direct relevance to prognosis. Study of early-onset cancer has often proved a fruitful resource for the identification of the nature and function of cancer susceptibility genes. In a study of colorectal cancer with stable microsatellite DNA, we describe 22 early-onset tumours (mean age=33), compared with 16 late-onset tumours (mean age=68). Both groups contained carcinomas with the MACS phenotype, characterized by near diploid DNA content, as defined by flow cytometry, and minimal chromosome arm deletion or amplification (six or less events per genome), determined by comparative genomic hybridization (CGH). Minimal chromosome imbalance correlated strongly with diploid DNA content (P<0.001). The proportion of MACS cancers was significantly greater in early-onset as compared to late-onset tumours (64 vs 13%, P=0.005). Of the chromosome arm imbalances commonly observed in late-onset tumours, only 18q- was observed more than twice amongst the 14 early-onset MACS tumours. Seventy-nine per cent of these MACS tumours were located in the distal colon, and 69% were at advanced clinico-pathological stages (with lymph node or distant metastasis). A positive family history of colorectal or other cancers was elicited in seven patients in the MACS early-onset group, and one additional patient in this group had a metachronous ovarian cancer. The results suggest that MACS cancer may have a genetic basis different from either MIN or CIN, and further studies of these cancers may lead to discovery of new mechanisms of colorectal carcinogenesis and cancer susceptibility.
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Chan AO, Chu KM, Yuen ST, Leung SY, Lam SK, Wong J. Synchronous gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma in association with Helicobacter pylori infection: comparing reported cases between the East and West. Am J Gastroenterol 2001; 96:1922-4. [PMID: 11419851 DOI: 10.1111/j.1572-0241.2001.03895.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The association of Helicobacter pylori infection with synchronous gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma is rare. Three Chinese patients (M:F = 1:2) who were 71, 58, and 75 yr of age were diagnosed to have gastric adenocarcinoma (2 patients) and gastric lymphoma (1 patient) on endoscopic biopsies. Distal gastrectomy was performed in all of them. Histological study of the three resected specimens revealed synchronous gastric adenocarcinoma and MALT lymphoma. H. pylori infection was found in two patients. A literature search revealed another 29 patients with synchronous tumors in whom H. pylori status was examined. Overall, H. pylori infection was found in 78% of 32 patients. The majority of lymphoma was low grade (75%) and was larger than carcinoma (81%). The majority of carcinoma (65.6%) was early. This suggested lymphoma might develop before carcinoma or the presence of MALT lymphoma might increase the risk of developing carcinoma.
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Chan AO, Lam SK, Chu KM, Lam CM, Kwok E, Leung SY, Yuen ST, Law SY, Hui WM, Lai KC, Wong CY, Hu HC, Lai CL, Wong J. Soluble E-cadherin is a valid prognostic marker in gastric carcinoma. Gut 2001; 48:808-11. [PMID: 11358900 PMCID: PMC1728335 DOI: 10.1136/gut.48.6.808] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Gastric cancer remains a major cause of cancer mortality globally but no good prognostic tumour marker is available. Soluble fragment of E-cadherin protein has been reported to increase in the sera of patients with cancer and recently was found to be elevated in 67% of patients with gastric cancer. AIMS To investigate if serum soluble E-cadherin is a valid prognostic marker in gastric cancer. METHODS Concentrations of soluble E-cadherin from 116 patients with histologically confirmed gastric adenocarcinoma and 40 healthy subjects were measured using an immunoenzymometric method with a commercially available sandwich ELISA kit based on monoclonal antibodies. RESULTS The logarithm of the means of soluble E-cadherin concentration was significantly higher in patients with gastric cancers (mean 3.85 (SD 0.28)) than in healthy subjects (3.71 (0.18)) (p=0.001), and in palliative/conservatively treated cancers (3.91 (0.35)) than in operable cancers (3.78 (0.19)) (p=0.015). The logarithm of the concentrations correlated with tumour size (p=0.032) and carcinoembryonic antigen concentrations (p=0.001). The cut off value calculated from discriminant analysis on operability and inoperability/palliative treatment was 7025 ng/ml. Soluble E-cadherin concentrations higher than this cut off value predicted tumour (T4) depth invasion (p=0.020, confidence interval (CI) 1.008-1.668) and palliative/conservative treatment (p=0.023, CI 1.038-2.514). In contrast, the relative risks for lymph node (N2) metastasis, distant metastasis, and stage III/IV disease were 1.41, 1.33, and 1.55 respectively, despite not reaching statistical significance. CONCLUSION Serum soluble E-cadherin is a potential valid prognostic marker for gastric cancer. A high concentration predicts palliative/conservative treatment and T4 invasion.
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Chan TL, Yuen ST, Ho JW, Chan AS, Kwan K, Chung LP, Lam PW, Tse CW, Leung SY. A novel germline 1.8-kb deletion of hMLH1 mimicking alternative splicing: a founder mutation in the Chinese population. Oncogene 2001; 20:2976-81. [PMID: 11420710 DOI: 10.1038/sj.onc.1204376] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2000] [Revised: 01/24/2001] [Accepted: 02/12/2001] [Indexed: 12/24/2022]
Abstract
We have previously reported that there is a high incidence of microsatellite instability (MSI) and germline mismatch repair gene mutation in colorectal cancer arising from young Hong Kong Chinese. Most of the germline mutations involve hMSH2, which is different from the mutation spectrum in the Western population. It is well known that alternative splicing is common in hMLH1, which complicates RNA based mutation detection methods. In contrast, large deletions in hMLH1, commonly observed in some ethnic groups, tend to escape detection by exon-by-exon direct DNA sequencing. Here we report the detection of a novel germline 1.8 kb deletion involving exon 11 of hMLH1 in a local hereditary non-polyposis colorectal cancer family. This mutation generates a mRNA transcript with deletion of exons 10-11, which is indistinguishable from one of the most common and predominant hMLH1 splice variants. A diagnostic test based on PCR of the breakpoint region led to the identification of an additional young colorectal cancer patient with this mutation. Haplotype analysis suggests that they may share a common ancestral mutation. Our results caution investigators in the interpretation of alternative splicing and have important implications for the design of hMLH1 mutation detection strategy in the Chinese population.
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